The invention relates to an encoder which is connected to a motor and is equipped with a reflecting sensor, a timing disc and a circuit board. The circuit board contains all of the components, such as resistors and contact strips, necessary for operation of the sensor.
The reflecting sensor is disposed in a housing together with the timing disc which is to be adjusted on the motor shaft so as to be in axial alignment therewith. The housing is attached to the by a flange at the output side of the motor shaft.
A known design of the encoder is described on pages 1 to 70--of the HP handbook. Here, a base plate is screwed to the flange plane of the motor and the timing disc then precisely aligned on the shaft via an adjusting device. The housing is pressed onto the base plate from above and secured by a rocking cam.
The timing disc is mounted in the housing and a locking mechanism of large diameter is used. For operation of the locking mechanism, the known encoder must be accessible from the upper side of the housing so that the housing cover needs to be large. Therefore, the sensor must be arranged relatively far from the middle of the timing disc.
With this type of housing design, the width and height of the housing are significantly larger than required by the individual elements. It has also been found that substantial time, as well as special tools, are required for assembly and adjustment. Furthermore, under unfavorable circumstances, readjustment is necessary.